Such a FM receiver has been known that automatic tuning to the broadcast wave is attained by provision of an auto-scanning circuit and a scanning-stop circuit. This conventional FM receiver has its constitution that the instruction to the scanning-stop circuit is issued solely as a squelch signal and that when the FM-receiver catches a broadcast wave and a squelch signal is issued, immediately the scanning-stop circuit acts on this squelch signal and a scanning-stop signal is issued to cease the scanning. In this type of FM receiver, there is no specific hindrance when the scanning is done with a scanning step wider than the receiver band width; but when the scanning is done with a scanning step narrower than the receiver band width, there is such a drawback that the scanning-stop circuit will come into action considerably before an exact tuning frequency is attained and in consequence, a perfect tuning will not be assured.
For the solution of the above-mentioned drawback, there is such a FM receiver that a window comparator is provided on the latter part of a demodulation circuit and an AND circuit is provided at the preceeding part of the scanning-stop circuit, whereby it is determined by using the window comparator whether or not a demodulation voltage is within the range of the reference voltage, and automatic tuning is conducted by using both of the demodulation voltage and the squelch signal. In this window comparator, a DC component of the demodulation voltage is utilized. The window comparator outputs demodulated signal towards the AND circuit when the DC component of the demodulation voltage falls in within the reference voltage. However, when the demodulated signal is inputted into the AND circuit as it is, the distinction is not made between the tuned one and no-tuned one. Therefore, there is such a problem that even though the tuning is not conducted, an output signal is issued from the AND circuit to the scanning-stop circuit; the scanning stop is carried out while the precise tuning is not attained, which renders the window comparator with the above-mentioned problem to be impracticable.